Pornographic actress Stormy Daniels alleges she had an affair with President Donald Trump during the months after first lady Melania Trump gave birth to their son, Barron Trump. (Tom Williams/CQ Roll Call file photo)

As special counsel Robert S. Mueller III continues to probe members of President Donald Trump’s 2016 campaign for possible collusion with Russia, some lawmakers have raised ethical concerns over the president’s alleged cover-up of an affair with porn actress Stormy Daniels.

Reps. Kathleen Rice of New York and Ted Lieu of California, both former prosecutors, have asked the FBI to investigate payments from Trump’s lawyer, Michael Cohen, to Daniels, who filed a lawsuit Tuesday against the president in Los Angeles Superior Court.

In the lawsuit complaint filed Tuesday, Daniels, whose real name is Stephanie Clifford, states that her nondisclosure agreement regarding her alleged 2006 affair with Trump is invalid because Trump never actually signed the document — only Cohen and Daniels did.

According to the lawsuit, Daniels’ affair with Trump lasted “well into 2007.”

The suit alleges that Cohen tried to intimidate Daniels into silence on the matter as recently as Feb. 27.

“To be clear, the attempts to intimidate Ms. Clifford into silence and ‘shut her up’ in order to ‘protect Mr. Trump’ continue unabated,” the suit claims. “On or about February 27, 2018, Mr. Trump’s attorney Mr. Cohen surreptitiously initiated a bogus arbitration proceeding against Ms. Clifford in Los Angeles.”

The suit also alleges Trump must be aware of Cohen’s attempts to silence Daniels, since New York bar rules require Cohen to keep his client informed at all times.

The president has not publicly commented on the alleged affair, which is said to have occurred in the months after his third wife, Melania Trump, gave birth to their son, Barron.

White House spokesman Raj Shah told members of the press he had never asked the president about the alleged relationship, NBC reported.

Cohen has acknowledged the payment, but has not publicly said what the payment was for. He has also said he paid out of his own pocket and was never reimbursed.